Help with lower ball joints on a 71 chevy

[71GMCStepside]

I hope someone can help me out. I'm prepping the frame of my 71 chevy. Last weekend I took the cab loose and managed to tilt it up on it's back (Talk about heavy!) so it's out of the way for me to clean up the frame underneath it as well as the frontend while I'm at it. The cab is the only thing I left on the frame, by the way. Anyway, I've powerwashed and degreased and scraped and degreased, etc.. This afternoon, I jacked up the front end and removed the stock coil springs (I've got a new set of 2in drop to go on). I noticed that one of the lower ball joints is shot.
Does anyone know how to remove these crazy things from the lower A-frame? They appear to be the original balljoints and I didn't have any trouble popping them loose from the caliper or whatever it's called to get the coils out, but the bottoms are giving me hell.

Any help would sure be appreciated.

Thanks!